Lensed fiber optic ferrule with simplified molding

ABSTRACT

A fiber optic ferrule has a main body with a top surface and a bottom surface and extends between a front end and a back end. The front face includes a recessed portion with a plurality of optical lenses. The front face is configured to allow for the plurality of lenses to be on an angle relative to the front face and the fiber optic ferrule will have not any undercuts and allow the fiber optic ferrule to be ejected from a mold without engaging any portions of the mold.

REFERENCE TO RELATED CASE

This application claims priority under 35 U.S.C. § 119 (e) to U.S.provisional application No. 62/930,754 filed on Nov. 5, 2019, thecontents of which are hereby incorporated by reference in theirentirety.

BACKGROUND OF THE INVENTION

Many types of single and multi-fiber fiber optic ferrules haveintegrated lenses and are available in the fiber optic connectorindustry today. These ferrules are made, at least partially, from anoptically clear material. One such lensed ferrule is the PRIZM® MT®ferrule (or, PMT ferrule) provided by the Applicant. The PMT ferrule haslenses on its end-face. The lenses are positioned generally along thesame plane that is orthogonal to the optical beam propagatingtherethrough. Molding the integral lenses and the ferrule requires twoor more moving parts of the mold.

There is a need in the fiber optic connector industry to continuouslyimprove the loss performance of current multi-fiber lensed ferrules. Onelimiting factor has its roots in the basic manufacturing (molding)process. Current molding processes for lensed ferrules have two or moremoving parts that need to move prior to the finished ferrule beingejected from the mold. One of the moving parts of the mold is the moldcore that creates the lenses that are adjacent to the end face of theferrule. By requiring the lens core to move between every injectioncycle, there is added uncertainty in controlling the location of thelens core relative to the rest of the mold. Since the ferrule is ejectedin a direction perpendicular to the end face, it is advantageous tocreate a ferrule end face with a refractive lens that does not containan undesirable undercut relative to the ejection direction.

Thus, there is a need for a to create a ferrule end face with arefractive lens that does not contain an undesirable undercut relativeto the ejection direction. Applicant has developed a new type of alensed ferrule, where the core that holds the lenses is fixed and doesnot move at the end of the molding process when the ferrule is ejected.Only the core that creates the guide pin holes or alignment features ofthe ferrule moves back and the ferrule is released from the mold.

SUMMARY OF THE INVENTION

The present invention is directed to a fiber optic ferrule for receivinga plurality of optical fibers in optical fiber support structures thatincludes a main body extending between a front end and rear end, themain body having a top surface and a bottom surface, the top surface andthe bottom surface having different lengths between the front end andthe rear end, a longitudinal axis extending between the front end andthe rear end and parallel to the optical fiber support structures, afront face at the front end of the main body, the front face beingnon-perpendicular to the longitudinal axis, a recessed portion at thefront face, a plurality of optical lenses within the recessed portion,wherein the front face has a plurality of points that lie on a pluralityof vertical axes extending between the bottom surface and top surface,wherein each of the plurality of points are even with or rearward of theeach of the plurality points thereabove.

In some embodiments, the plurality of optical lenses are in at least onerow extending between side surfaces of the fiber optic ferrule.

In some embodiments, the length of the bottom surface is shorter thanthe length of the top surface.

In other embodiments, the fiber optic ferrule is ejected in a directionparallel to the vertical axes after a molding process.

In some embodiments, each of the plurality of points are even with orforward of the each of the plurality points therebelow.

In yet another aspect, there is a fiber optic ferrule for receiving aplurality of optical fibers in optical fiber support structures thatincludes a main body extending between a front end and rear end, themain body having a top surface and a bottom surface, the top surface andthe bottom surface having different lengths between the front end andthe rear end, a longitudinal axis extending between the front end andthe rear end and parallel to the optical fiber support structures, afront face at the front end of the main body, the front face beingnon-perpendicular to the longitudinal axis, a recessed portion at thefront face, a plurality of optical lenses within the recessed portion,wherein the front face has a plurality of points that lie on a pluralityof vertical axes extending between the bottom surface and top surface,wherein each of the plurality of points are even with or forward of theeach of the plurality points therebelow.

And in yet another aspect, there is a provided a fiber optic ferrule forreceiving a plurality of optical fibers in optical fiber supportstructures that includes a main body extending between a front end andrear end, the main body having a top surface and a bottom surface, thetop surface being longer than the bottom surface, a longitudinal axisextending between the front end and the rear end and parallel to theoptical fiber support structures, a front face at the front end of themain body, the front face being non-perpendicular to the longitudinalaxis, a recessed portion at the front face, a plurality of opticallenses within the recessed portion, wherein the fiber optic ferrule ismoved in a direction orthogonal to the top surface post molding.

It is to be understood that both the foregoing general description andthe following detailed description of the present embodiments of theinvention are intended to provide an overview or framework forunderstanding the nature and character of the invention as it isclaimed. The accompanying drawings are included to provide a furtherunderstanding of the invention, and are incorporated into and constitutea part of this specification. The drawings illustrate variousembodiments of the invention and, together with the description, serveto explain the principles and operations of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of one embodiment of a fiber optic ferruleaccording to the present invention;

FIG. 2 is front view of the fiber optic ferrule in FIG. 1 ;

FIG. 3 is a left side elevation view of the fiber optic ferrule in FIG.1 ;

FIG. 4 is a left side elevation view of a cross-section of the fiberoptic ferrule in FIG. 1 ;

FIG. 5 is a perspective view of a portion of the front face of the fiberoptic ferrule in FIG. 1 ;

FIG. 6 is a schematic of a portion of the front of the fiber opticferrule in FIG. 1 showing the points along a vertical axis; and

FIG. 7 is a schematic of a portion of the fiber optic ferrule in FIG. 1illustrating the relationships of the components of the fiber opticferrule.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the present preferredembodiment(s) of the invention, examples of which are illustrated in theaccompanying drawings. Whenever possible, the same reference numeralswill be used throughout the drawings to refer to the same or like parts.

Applicant notes that the term “front” or “forward” means that directionwhere the fiber optic connector and/or the ferrule would meet withanother fiber optic connector or device, while the term “rear” or“rearward” is used to mean the direction from which the optical fibersenter into the fiber-optic ferrule or fiber optic connector. Each of thefiber optic ferrules will therefore have a front and rear, and the twofronts or forward portions of the fiber optic ferrules would engage oneanother. Thus, in FIG. 1 , the “front” of the fiber optic ferrule is onthe left side of FIG. 1 and “forward” is to the left and out of thepage. “Rearward” or “back” is that part of the fiber optic connectorthat is on the right side of the page and “rearward” and “backward” istoward the right and into the page.

One embodiment of a fiber optic ferrule 100 according to the presentinvention is illustrated in FIGS. 1-7 . The fiber optic ferrule 100 hasa main body 102 extending between a front end 104 and a rear end 106,the main body 102 has a forward portion 108 and a rearward portion 110.The forward portion 108 is separated from the larger rearward portion110 by a shoulder 112. The fiber optic ferrule 100 may not have thelarger rearward portion 110, but whole main body 102 would have the sameheight and width as the forward portion 108.

The fiber optic ferrule 100 has a top 114, a bottom 116, and two sides118, 120. The forward portion 108 has a top surface 130 and a bottomsurface 132, the top surface 130 and the bottom surface 132 havinglengths L1, L2, respectively. The lengths L1, L2 may be the differentor, in another embodiment, they may be same. As illustrated in FIGS. 1and 3 , the lengths L1, L2 are measured between the front end 104 andthe shoulder 112. If the fiber optic ferrule 100 were of a uniformheight and width as noted above, then the lengths could be measured fromthe front end 104 to the rear end 106. The two sides 118, 120 each havea side surface 134, 136, respectively (see FIG. 2 ). It should be notedthat the rearward portion 110 also has a top surface 130 a, a bottomsurface 132 a, and side surfaces 134 a, 136 a, respectively. While thetop surface 130 is illustrated as being the longer surface, it is alsopossible for the bottom surface 132 to be longer, so long as the mainbody has the appropriate configurations as described herein—thus it mayonly be a semantic change from “top” to “bottom.”

There is a front face 140 positioned at the front end 104. Preferablythe front face 140 has a recessed portion 142. There may also bealignment structures 144, which in one form takes the shape of guide pinholes. The alignment structures 144 may or may not open at the frontface 140 within the recessed portion 142. The recessed portion 142 maybe completely encircled by the front face 140, or the recessed portion142 may extend to the top 114 or the bottom 116 or one of the sides 118,120.

The main body 102 has an opening 150 that extends from the rear end 106towards the front end 104 to receive optical fibers within the fiberoptic ferrule 100. The main body 102 has optical fiber supportstructures 152 within the opening 150. The optical fiber supportstructures 152 could be micro-holes, v-shaped grooves or otherconfigurations that support and align the optical fibers. The fiberoptic ferrule 100 has a longitudinal axis A that is parallel to theoptical fiber support structures 152 and the optical fibers that areinserted into the fiber optic ferrule. See FIGS. 3 and 4 .

Turning to FIG. 3 , the effect of the differing lengths L1, L2 is thatthe front face 104 makes an angle α other than 90° with the longitudinalaxis A. Typically the angle α is about 84° but could be larger orsmaller depending on a number of factors, for example, return loss,fiber mode, etc. It should be noted that the fiber optic ferrule 100 isusually mated with another ferrule that has the same configuration butis flipped 180° about the longitudinal axis so that the two front faces104 are parallel to one another.

Turning to FIGS. 1-2 and 5-7 , the recessed portion 142 has a number ofdifferent areas that stretch across at least a portion of the front face140. As illustrated herein, there are two areas 160,162 with a pluralityof integral lenses 164 in rows. See FIGS. 2 and 6 in particular. It isalso possible that there be more or fewer rows on integral lenses in thefiber optic ferrule 100. There is also an area 166 above the first area160 of integral lenses 164. There is another area 168 that is betweenthe two areas 160,162 with the plurality of integral lenses 164.Finally, there is a third area 170 below the second area 162 of integrallenses 164.

For each row of integral lenses 164, each integral lens, or a portionthereof that is exposed, is at a tilt angle θ to the vertical/Y-axis.The term “integral” as aaplied to the integral lenses 164 refers to thelenses being molded together with the main body 102, and not beingpositioned separately onto the front face 140 or the recessed portion142 thereof. For example and with reference to FIGS. 6 and 7 , the toplens is shown at the tilt angle θ relative to the top lens tangent line.Likewise, the bottom lens is at the same tilt angle relative to thebottom lens tangent line. Typically, θ is approximately 22°.

With reference to FIG. 2 , there are a plurality of vertical lines oraxes B that can be used with reference to the front face 140. Each ofthese vertical axis B are perpendicular to the longitudinal axis A. Onlyfour vertical lines or axes B are illustrated in FIG. 2 . Indeed, thereare theoretically an infinite number of vertical lines or axes B thatcould be placed on the front face 140 of the fiber optic ferrule 100.The front face 140, including the recessed portion 142, is made up ofplurality of points 172 (indeed, also theoretically an infinite numberof points). FIGS. 6 and 7 are representations from the left side of thefiber optic ferrule 100 of some of the points 172 on the front face ofthe fiber optic ferrule along one of the vertical axes B. This viewallows for the description of the points 172 relative to the otherpoints along one of the vertical axes B that is not possible to see in afront view image, i.e., FIG. 2 .

The top 114 of the fiber optic ferrule 100 would be at the top of thepage (or even beyond) as only a portion of the front face 140 isillustrated in FIGS. 6 and 7 . It is the same consideration for thebottom 116, which is below where the figures are labeled. The solid darkline on the very left of the images is the front face 140, that makesthe angle α with the top 114 and bottom 116. As can be understood (andwith reference to FIGS. 3 and 4 ) the front face 140 at the top of thefiber optic ferrule 100 is the forward-most (the leftmost point in FIGS.3 and 4 ) point on the fiber optic ferrule 100 along the vertical axisB. The next solid line demonstrate the points 172 that make up therecessed portion 142 and includes the areas 160,162 with a plurality ofintegral lenses 164 and the spacing areas 166, 168 and 170 (and thefront face 140 if the figure showed such). For each point 172 along thefront face 140 and the recessed portion 142 and along the vertical axisB, the point directly above it is either even with or in front of (tothe left in FIGS. 6 and 7 ) that point. For example a point P1 (areference point) is illustrated in FIG. 6 as well as a second point P2.It is clear from FIG. 6 , that P2 is either directly above or in frontof (to the left) of P1. P2 is not behind or to the right of Pl,eliminating any undercut on the front face 140 of the fiber opticferrule 100. Conversely, using P2 as the first (reference) point, thenP1 (a point below P2) is either directly below or behind P2. Because ofthis relationship of the points 172 along the vertical axes, there is noundercut on the front face 140 of the fiber optic ferrule 100. Thisrelationship allows the fiber optic ferrule 100 to be ejected from moldin a vertical direction (perpendicular to the top surface 130) andupward in FIGS. 6 and 7 without removing or moving more of themold—e.g., that part that forms the front face 140.

As illustrated in FIG. 7 , the integral lenses 164 in area 160 arefurther to the left than the integral lenses 164 in the lower area 162.Again, this contributes to the elimination of the undercut in a typicalfiber optic ferrule where, if the lenses are aligned on a vertical axis,there would be areas of undercut. The integral lenses 164 may beportions of a sphere, although other non-spherical refractive surfacesthat are at a similar tilt as the integral lenses 164 could be used inanother embodiment.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the present inventionwithout departing from the spirit and scope of the invention. Thus it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. A fiber optic ferrule for receiving a plurality of optical fibers inoptical fiber support structures comprising: a main body extendingbetween a front end and a rear end, the main body having a top surfaceand a bottom surface, the top surface and the bottom surface havingdifferent lengths between the front end and the rear end; a longitudinalaxis extending between the front end and the rear end and parallel tothe optical fiber support structures; a front face at the front end ofthe main body, the front face being non-perpendicular to thelongitudinal axis; a recessed portion at the front face; a plurality ofoptical lenses within the recessed portion, wherein the front face has aplurality of points that lie on a plurality of vertical axes extendingbetween the bottom surface and top surface, wherein each of theplurality of points are even with or rearward of the each of theplurality points thereabove.
 2. The fiber optic ferrule according toclaim 1, wherein the plurality of optical lenses are in at least one rowextending between side surfaces of the fiber optic ferrule.
 3. The fiberoptic ferrule according to claim 1, wherein the plurality of opticallenses are in at least two rows.
 4. The fiber optic ferrule according toclaim 1, wherein the length of the bottom surface is shorter than thelength of the top surface.
 5. The fiber optic ferrule according to claim1, wherein the vertical axes are perpendicular to the longitudinal axis.6. The fiber optic ferrule according to claim 1, wherein the fiber opticferrule is ejected in a direction parallel to the vertical axes after amolding process.
 7. The fiber optic ferrule according to claim 1,wherein each of the plurality of points are even with or forward of theeach of the plurality points therebelow.
 8. The fiber optic ferruleaccording to claim 1, wherein each of the plurality of lenses is offsetfrom the longitudinal axis by an angle θ.
 9. The fiber optic ferruleaccording to claim 1, wherein the front end of the top surface isforward-most point of the fiber optic ferrule.
 10. A fiber optic ferrulefor receiving a plurality of optical fibers in optical fiber supportstructures comprising: a main body extending between a front end and arear end, the main body having a top surface and a bottom surface, thetop surface and the bottom surface having different lengths between thefront end and the rear end; a longitudinal axis extending between thefront end and the rear end and parallel to the optical fiber supportstructures; a front face at the front end of the main body, the frontface being non-perpendicular to the longitudinal axis; a recessedportion at the front face; a plurality of optical lenses within therecessed portion, wherein the front face has a plurality of points thatlie on a plurality of vertical axes extending between the bottom surfaceand top surface, wherein each of the plurality of points are even withor forward of the each of the plurality points therebelow.
 11. The fiberoptic ferrule according to claim 10, wherein the plurality of opticallenses are in at least one row extending between side surfaces of thefiber optic ferrule.
 12. The fiber optic ferrule according to claim 10,wherein the plurality of optical lenses are in at least two rows. 13.The fiber optic ferrule according to claim 10, wherein the length of thebottom surface is shorter than the length of the top surface.
 14. Thefiber optic ferrule according to claim 10, wherein the vertical axes areperpendicular to the longitudinal axis.
 15. The fiber optic ferruleaccording to claim 10, wherein the fiber optic ferrule is ejected from amold in a direction parallel to the vertical axes.
 16. The fiber opticferrule according to claim 10, wherein each of the plurality of lensesis offset from the longitudinal axis by an angle θ.
 17. The fiber opticferrule according to claim 10, wherein the front end of the top surfaceis forward-most point of the fiber optic ferrule.
 18. A fiber opticferrule for receiving a plurality of optical fibers in optical fibersupport structures comprising: a main body extending between a front endand a rear end, the main body having a top surface and a bottom surface,the top surface being longer than the bottom surface; a longitudinalaxis extending between the front end and the rear end and parallel tothe optical fiber support structures; a front face at the front end ofthe main body, the front face being non-perpendicular to thelongitudinal axis; a recessed portion at the front face; a plurality ofoptical lenses within the recessed portion, wherein the fiber opticferrule is moved in a direction orthogonal to the top surface postmolding.